For one thing, the Christian doctrine of grace is really reprehensible. "Grace" means that humans are "depraved" because of Adam's fall, that they cannot rationally respond to an offer of "salvation" from Christ, so the Christian god actually overrides man's will so he will "repent" and "be saved", and that Christ's offer is meant for the "elect", which is independent of one's moral character or good works. To the extent that this nonsense is meaningful, it is evidently quite sick: it denigrates human beings as worthless wretches, and it allows those who believe they are among the "elect" to feel superior to everyone else.
For another, the song was written by a slave trader, John Newton, who underwent a religious conversion after a life-threatening storm at sea (but nevertheless continued in the slave trade for several years afterwards). How this became a civil rights anthem is anyone's guess, but it seems wildly inappropriate.
Far better, in my opinion, is "We Shall Overcome", which is both lyrically and melodically superior.
So I have to admit that when President Obama sang "Amazing Grace" at the eulogy for Rev. Clementa Pinckney, I was not particularly moved at all. However, I certainly recognize that, for the community he was addressing, the song has strong resonance. But "We Shall Overcome" would have been a much better choice.
And even worse was Obama's remarks on religion:
"Blinded by hatred, [the killer] failed to comprehend what Reverend Pinckney so well understood — the power of God’s grace... This whole week, I’ve been reflecting on this idea of grace. The grace of the families who lost loved ones; the grace that Reverend Pinckney would preach about in his sermons; the grace described in one of my favorite hymnals, the one we all know — Amazing Grace. How sweet the sound that saved a wretch like me. According to the Christian tradition, grace is not earned. Grace is not merited. It’s not something we deserve. Rather, grace is the free and benevolent favor of God."
I'm sorry, Mr. President, I think "grace" is one of the most repulsive of all Christian beliefs.
"The hands that help are better far than lips that pray." -- Robert Ingersoll